Electrical heating device



Dec. 29, 1936. J H s n-H ELECTRICAL HEATING DEVICE Filed Nov. 25, 1931 6 Sheets-Sheet 1 fiy/ Hya: .3 7 f 2 a0 INVENTOR Dec. 29, 1936. J. H. SMITH 2,065,760

ELECTRICAL HEATING DEVICE Filed Nov. 25, 1931 6 Sheets-Sheet 2 INVENTOR Dec. 29, 1936. J. H. SMITH ,065,760

ELECTRICAL HEATING DEVICE Filed Nov. 25, 1931 6 Sheets-Sheet 4 INVENTOR Dec. 29, 1936. J, s H 2,065,760

ELECTRICAL HEATING DEVICE Filed Nov. 25, 1931 6 Sheets-Sheet 5 N Q N r\ M g a INVENTOR Dec. 29, 1936. J. H. SMITH ELECTRICAL HEATING DEVICE Filed Nov. 25, 1931 6 Sheets-Sheet 6 Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE 18 Claims.

My invention relates to electrical heaters, and further extension of the ideas first worked out in my Patent No. 1,771,273, dated July 22, 1930, and applications of the new principles. There I describe and claim an electrical heating device comprising a network of interconnected resistors and current supplying conductors of better current conducting properties than the resistors. The fundamental principles of the compound heating network described in that patent are further developed in this application, as hereinafter more specifically pointed out.

In the above patent the outside impressed electromotive force was carried bybranching conductors to elemental resistor units arranged symmetrically and in parallel circuits for the purpose of heating an insulating body, whether opaque or transparent. There the voltage was controlled by a rehostat in the circuit which effected heat regulation within the insulating body.

This distinctive common feature of the original patent and these developments of it, is the use of compound resistive networks embedded in a relatively insulating body, with heat radiated directly from said network and heat absorption in the insulating body with secondary radiation therefrom.

In the present application employment is made of the step-up and step-down transformer, and the equivalent auto-transformer, in combination with resistor elements arranged in symmetrical pattern on branching conductors, the whole constituting a plurality of electrically connected parallel and series-parallel circuits, forming a compound resistive network. A very wide range of voltage is made available for the elemental resistor units.

The combination of two distinct methods of dividing the circuit is employed in this application. The flexibility of the transformer and auto transformer in subdividing the impressed voltage or in multiplying the impressed voltage, operations commonly referred to as step-up and "step-down", and the sub-divisions of the conductor circuits in my Patent No. 1,771,273, ail'ord the greatest possible flexibility in applying voltage to the resistor elements as well as make possible the use of a very wide range of potentials.

Also selected input voltage can be greatly enlarged over the entire sheet of assembled resistor networks while holding the resistor units at a comparatively low voltage, by using the step-up transformer to enlarge the service voltage and apply that higher voltage to the terminal conductors of the resistor sheet.

This procedure would create unduly high voltage, were it not for extensive subdivision by intermediate non-continuous conductors which distribute electricity to the resistor units, feeding in parallel thereto, but being themselves in series relation to each other.

In the compound resistive network, the voltage drop from conductor to conductor is capable of being held constant by tying in intermediate tap conductors through taps to the transformer or auto transformer. This constitutes a distinct and novel use of the auto transformer for the purpose of stabilizing the voltage within the resistive networks. So if the transformer carries equi-spaced taps throughout its winding and these are joined to equi-spaced conductors in the resistive sheet there will result a uniform voltage drop from one tap conductor to the next tap conductor.

The taps from the transformer thus run to a succession of non-continuous conductors in the compound network having resistive wires lying there-between. If now the resistive wires are again crossed by intermediate conductors lying between the aforesaid tapped conductors, the voltage drop will be held uniform by the said intermediate conductors.

If the intermediate conductors are not tied into the transformers, they may be termed floating conductors in that the voltage upon them is not held constant in the same manner as with the tap conductors. They are discontinuous with the other conductor system. 5

Their function is to collect current from a group of resistive wires and distribute the same to another group of resistive wires. There may, of course, be a number of such intermediate conductors which may be termed floating, in that they have no direct connection with the conducting wires upon which a constant voltage is impressed.

There is always a set of resistive wires lying between the floating conductor and the main conductors. Chiefiy, the effect of these intermediate floating conductors is to uniformize electromotive forces throughout the resistive sheet.

It is to be noted that both tap and floating conductors may be employed within the compound resistive network.

In my Patent No. 1,771,273 the elemental resistor unit there shown was in the form of a square open at two opposite corners and closed at the diagonally opposite corners, with three cross resistors. There was no intention of limiting the resistor unit, and in this application are shown other geometrical patterns for the resistors. These resistors can be of any selected number and of varying diameters. lengths or of material of different resistivity even in the same resistor element, or selected groups may be built up so that unequal quantities of energy are released in different units or groups thereof in the compound network. 7

The resistive networks may be adapted to receive two-phase and three-phase current in a single resistive element. This is done by grouping single-phase resistor units into phase relation with each other and also by connecting groups together to constitute conducting paths of a wave-finding type suitable for any phase distribution.

Application of these compound resistive networks is made to a window, a radiant heater and a wall heater. The essential part of the latter can be employed as a portable heater. In all cases the electricity is converted into heat directly at the place of utilization.

In the wall or portable heater, the resistive grids are assembled in multiple within insulating blocks of a flat type which may be quite thin because of the small space taken up by a compound resistive network. These flat blocks are then assembled close together in parallel position with sufficient separation to permit entrant air to be heated by convection.

A suitable circuit for using networks comprises a transformer having a plurality of taps, a selector switch or controller for selecting the desired voltage and the network itself. If networks occur in multiple a second controller selects the number of them in circuit.

By employing a controller acting upon taps of the transformer each elemental sheet or block receives a voltage and heat input variable at will. A second controller in combination with the first takes the regulated voltage and applies it to successive elemental heating sheets, or blocks, cutting them selectively in or out of the circuit, with or without thermo links. In the circut drawings are thermo links acting on the voltage and controlling the number of blocks in circuit, though this may be regulated by hand.

In the application to a radiant heater the same arrangement of controllers and auto transformers with thermostatic control is employed upon radiant units composed of resistive sheets formed into blocks which are placed in multiple connection in front of parabolic mirrors of metal having a high reflectivity such as chromium and aluminum. They may be polished to increase the reflectivity. These parabolic mirrors also serve to form with the radiant units a semi-closed conducting space in which entrant air currents rise and are heated in their passage over the radiant units and by contact with the mirror surface.

In the application to an electrically heated window, a sheet of glass contains one or more sheets of compound resistive networks closely parallel to each other and placed next to the room space to be heated so that as much of the insulating glass shall lie between the resistive networks and the cold exteriorly exposed surface as possible. Two or more sheets of such electric glass may be placed in parallel position so that air entering through the lower sash may rise between the sheets of glass, taking heat therefrom by convection, and discharging at the upper sash through apertures which enter the room. Such a ventilating window operates much like the well known house radiator, but has the advantage of occupying no useful space and has a greater heating column.

Similarly, the wall heater described above, when in a portable shape, will occupy very much less space than the common cast-iron radiator using steam or hot water as a heat source.

Instead of glass, other body material may be used, the whole enclosed in a casing, with or without recirculation of air, forming an indirect all-electric air heater of high efficiency and compact shape, well adapted for fan operation and capable of very high temperatures.

The accompanying drawings illustrate several present preferred embodiments of the invention, in which Figure 1 shows an auto transformer in electrical connection with a resistive sheet in which a small fraction of the service voltage applied to the auto transformer is impressed upon the whole resistive sheet and said reduced voltage is further divided across the whole number of elemental resistive units. All of the conductors except the terminal ones are non-continuous, floating and in series relation. These floating conductors have one chief function. namely, to hold the voltage constant on all contiguous resistor elements. They are referred to also as intermediate conductors. Both main conductors receiving a directly impressed voltage, as well as the intermediate conductors, are also designated indifferently as tree conductors because of the circuit branching which occurs in both types.

In Figure 2 the voltage impressed upon the resistive network is greater than the service voltage to the auto transformer and here again the conductors are of the floating type.

In Figure 3 the impressed voltage is less than the service voltage and each of the intermediate conductors is so tied to transformer taps that equal voltages are impressed upon these tied-in conductors.

In Figure 4 is shown the combination of an auto transformer with a resistive network composed of floating and tied-in conductors in alternate arrangements. Obviously, any grouping or segregation of floating and tied-in conductors may be employed. It will be noted that the impressed voltage on any resistor element is greater than the service voltage.

In Figure 5 is shown an auto transformer in combination with a compound resistive network in which the conductors are further branched upon a smaller resistor unit, with outside taps, so that the impressed voltage may be regulated on the high side of the transformer or auto transformer. The cut-down voltage impressed by the auto transformer is carried across the entire resistive network and again divided by the tree conductors before reaching the resistor unit. This arrangement gives a variable voltage on each resistor element.

In Figure 6 likewise a reduced voltage is applied to the resistive network and equally spaced taps from the auto transformer are tied in at every fifth conductor square or resistor element.

In Figure 7 is shown a rectangular tree conductor pattern in which the resistor element is a pair of cross resistive wires being composed of a straight resistive wires through all conductor squares.

In Figure 8 both diagonal and cross resistive wires are used upon rectangular conductors.

In Figure 9 two pairs of cross resistive wires comprise the resistor element.

In Figures 7, 8 and 9 it is obvious that the patterns may be extended indefinitely because of the complete symmetry of the arrangement.

In Figure 10 is shown a diagonal arrangement for the resistor wires where the conductor wires are in rectangular formation.

In Figure 11 is shown a triangular pattern for the resistor units which is very efficient and easily adapted. In this view the resistive wires are very finely curled in a helical path, which may be employed in any resistor element instead of straight wires elsewhere shown.

In Figure 12 is shown an interlacing pattern of hexagonal conductors with resistors crossing conductors at right angles by three groups of straight resistive wire at 60 degrees to each other forming equilateral triangles with the apices at the center of the hexagon conductor units. Obviously, all resistors may be curled or coiled, as in Figure 11.

In Figure 13 is shown a circuit diagram comprising a group of four resistive blocks, each having a compound resistive network, all in parallel connection to a multitap controller, so that each can be successively cut in or taken out of the circuit. This group controller is connected with a controller on the auto transformer so that successively increased voltages can be impressed upon the resistive blocks. Thermostats are shown in each circuit.

In Figure 14 is shown a resistive network which is adapted to receive three-wire singlephase, or three-wire two-phase supply.

In Figure 15 is shown a group of resistive networks in double star connection to receive three-phase supply.

In Figure 16 is shown a group of parallel current conductors of rectangular form separated in this view only for the purpose of clarifying the drawings, to show a wave-winding employed to connect every fourth conductor and then the intermediate ones are similarly connected so that a three-phase supply is carried throughout the entire sheet. Any resistor pattern may be used to cross the conductor wires. This is a closed delta circuit.

In Figure 17 is shown a vertical elevation of a wall heater in which the resistive blocks are arranged vertically and equi-spaced for the circulation of air admitted at the bottom of the heater.

A divided frame of metal or fire-resisting material carries the group and tap controllers with electric equipment in one compartment and the resistor blocks in the other compartment. The first is closed by a grille partially removed in this view to show the circuit arrangement and parts and the second compartment is covered by the same grille also. A curved deflector sheet, seen better in Figure 18, assists the movement of heated air from and through the heater. For an open room in a portable modification the deflecting plate is omitted, air rising straight from the resistive blocks.

A transformer is shown connected to a tapchanging controller, also a group controller, with thermo links.

In Figure 18 is shown a. sectional view on line XVIII of Figure 17, which discloses a complete resistive sheet within the heating block with the air openings thereunder and a wiring well shown at the top in which the upper leads of the successive heating blocks are picked up and carried over to the group controller. The heating blocks are shown keyed at the bottom in a perforated base plate and at the top securely held by heavy screws locking the block on the back of the frame.

In Figure 19 is shown a horizontal section taken on line XIX in Figure 17, showing the air ports in the base plate, and with the electric auxiliaries removed.

In Figure 20 is shown an elevation of the radiant heater containing four radiator units, each having within it a number of compound resistive networks. Obviously, the number of these radiators can be increased vertically and horizontally to cover any space, or they can be diminished even down to a single unit. The arrangement of transformer and controllers is the same as in Figure. 1'7.

In Figure 21 is shown a horizontal section, taken on line XXI of Figure 20', disclosing the shape of the parabolic reflectors and the method of attaching the radiator units to the frame of the heater, the whole being adaptable for inserting into a wall or being separately placed therebefore or utilized as of a portable form.

In Figure 22 is shown the front elevation of a portion of a window comprising two sheets of resistive networked glass, and a frame showing openings in the bottom for ventilating, and similar openings at the top so that heated air may rise between two parallel sheets of glass shown in the next figure.

In Figure 23 is shown a cross-section on line XXIII of Figure 22, disclosing a. window with parallel sheets of networked glass separated by spanners and wedged in the frame securely, there appearing, more particularly, the sash openings for ventilation, the lower of which opens inwardly as well as outwardly to the atmosphere with damper regulation of the air intake.

In Figure 24 is shown a sheet of glass in section disclosing location of resistive sheets therein which may be placed at any predetermined distance from the surfaces of the glass.

In Figure 25 is shown a circuit diagram for establishing series-multiple connections between groups of resistance sheets.

In Figure 1, I and 2 are terminals of a resistor element such as shown in Patent No. 1,771,273; that part of the resistive network embraced by l34-i5 is an electrical equiva-, lent to the circuit of the earlier patent in that the voltage impressed upon it is the same throughout, being a multiple type of compound network. In this Figure 1, points 3-4-6--5 form a similar network where 3 and 4 are terminals of a floating, independent, or intermediate noncontinuous conductor, and 5 and 6 are terminals for another intermediate, non-continuous conductor which interfits with the foregoing conductorto form resistor areas. The two foregoing groups of networks are now in series and the voltage from I to 5 is just double the voltage from I to 3, and so for the successive groups up to the final one ll-l2--|4- i3 here shown. The arrangement or grouping of pure multiple networks by the device of intermediate noncontinuous conductors constitutes a compound network of the series-multiple type. This type is shown also in succeeding Figures 2, 3 and 4.

In this particular drawing, Figure 1, a square type of resistor area is shown, though of course the pattern may be oblong, there being no limitations upon the number of cross resistor wires, nor is it essential that these resistor wires be equi-spaced within the resistor element, nor that they should be straight-lined, nor even that the pattern should be symmetrical within the area of the resistor element.

1, 8 and 9, 10 are successively adjacent conductor trees supporting branch conductors which in later figures of the drawings are further branched so that a selected electromotive force may be impressed upon an insulating area or region of definitely limited area. or space, as small as may be desired.

End conductors i, and 13, I4 are in electrical connection with a transformer or auto transformerfas shown in Figure l at I6, I! upon which is impressed at I6 and I! an electromotive force originating in an ulterior source or service circuit.

In this type of circuit arrangement only a fractional part of the outside voltage is impressed upon the assemblage of resistor elements hereinafter designated as a resistive sheet", and this voltage in turn is subdivided by the floating, intermediate non-continuous conductors, from which it is obvious that arm selected or computed voltage for the resistor element may be conveniently applied.

Resistor elements in Figure l are identical with that shown in my Patent No. 1,771,273, but the conductor arrangement here is such as to put groups of resistor elements in series. Between conductors l-l5 and 3-4 are a range or group of resistor elements taking identical voltage in complete parallel arrangement. A similar adjacent group lies between tree con ductors 34 and 5-B, and for successive sets or groups across the resistive sheet to conductor l3--l4. But it will be observed that the successive sets or groups so described are in series relation to each other, there being with equispaced conductors a definite though equal voltage drop from group to group. While this is a parallel-series arrangement of conductors, the pattern of the resistive sheet is identical with that shown in Figure l of my Patent No. 1,771,- 273, except that the tree conductors are here differently connected at their terminals to produce a compound network in parallel-series arrangement.

In Figure 2, i9, impress upon a resistive sheet a greater voltage than the service voltage 2|, 22. In this figure the intermediate conductors lying between the terminal conductors are independent and floating conductor members, just like in Figure 1.

In Figure 3 the resistive sheet is identical with that in Figure 1, but the intermediate conductors are tied into the auto transformer. The tree conductor 24-25 is tied in to the auto transformer at 26, the next tree conductor 2|--28 is tied in to the transformer at 29, and so for tree conductor -3l at 32, and likewise for successive tree conductors. It will be observed that this arrangement of circuits impresses upon each range of elemental resistors lying between adjacent trees 2425 and 21--2U a definite fixed fractional part of the service voltage, and likewise between 21- 28 and 3l3l.

It is also clear that the voltage builds up on the resistive sheet in passing from conductor 25 to conductor 28 and that the voltage impressed upon the entire resistive sheet is a definite fractional part of the total service voltage applied at 23, II. It will be observed that the transformer taps between points 23, 34, which are connected to successive tree circuits need not be equally spaced on the auto transformer, and that different voltages may be impressed upon successive ranges of elemental resistors and different quantities of heat released therein. Such an unequal spacing of the transformer taps would result in band heating, in that upon equal areas there would be released unequal quantities of heat through the columns of resistor elements. Such quantities are, moreover, absolutely fixed in their proportions by tying the tree conductors tothe transformer taps. In this connection it is to be noted that varying the number of resistor wires within a resistor element or selecting wires of different resistivity or of different lengths according to the selected pattern gives a freedom in spotting unequal quantities of heat in a row, range or column of resistor elements, or even in the resistor elements themselves. The flexibility in the distribution of heat upon a resistive sheet is indeed perfect, there being complete control of the heat release in these respects: (1) branching of the tree conductors narrows the area of heat release; (2) resistor wires of varying length, diameter and resistivity permit full control of the heat release within the area of a single resistor element; and (3) the application of the service voltage through a transformer having taps tied in to the tree conductors gives a very wide choice in the voltage impressed upon a row, range or group of resistor elements. In Figures 1 and 3 the taps are inside taps.

In Figure 4 is shown an arrangement whereby only alternate tree conductors are tied in to the auto transformer and the service voltage is less than that applied across even a single element and the voltage impressed upon the whole resistive sheet is many times the service voltage. This is just the reverse of Figure 1, where the service voltage is fractionated. Points -36 are an end conductor connected in to auto transformer at 46. Points 31-38 are an independent tree conductor and the next tree conductor 39-40 is connected in to the auto transformer at 48. Similarly tree conductor 4l42 is tied in at 49 and end conductor 4344 is tied in at auto transformer terminal 50. Taps 4B, 48, 49, 50 are equi-spaced and the voltage gradient through the compound resistive network is uniform here. Thus it appears that the service voltage may,

by these devices, be stepped up or stepped down upon the resistor element ad libitum from the service voltage.

In Figure 5 are shown tree conductors running horizontally and further branched to reduce the area of the resistor square, with outside taps to the service voltage. Iii-52 is the elemental resistor square brought by branching to one-ninth of the area of the resistor elements in the preceding figures. Upon this greatly reduced area is impressed the full voltage applied to the whole resistive sheet lying between 53, 54, which is a fractional part of the service voltage impressed between 55 and 56. Points 51, 58, 59, and GI are outside taps, which in a later figure of the drawings, are carried to a tap control for successively reducing, or enlarging upon the service voltage. The resistor wires lying between the branches of the tree conductors are shown at 62 and G3.

In Figure 6 is shown a resistive sheet in which 15 the tree conductors are still further branched, as at 64, 86, 66 and the transformer has inside taps connected to each successive tree conductor, as in Figure 2, at points. 81, 68, 68 and I0, the whole impressed electromotive force being arbitrarily reduced by the inside taps tied to the intermediate conductors. At the lower right corner are shown resistive wires as before.

In Figure 7 with rectangular conductor arrangement, being a typical square taken from Figure 5, single cross resistive wires are employed in the resistive element.

Points 1I--I2 and 13-14 are a pair of adjacent conductors being parts of adjoining tree conductors and 'I5--I6 and 'III8 are crossing resistor wires in electrical connection with the conductor wires at I9, 80, 8I and 82, forming an elemental resistor unit, being one of nine similar such units here shown. Obviously the pattern may be extended, as in preceding figures.

In Figure 8, both diagonal and cross resistive wires are used upon rectangular conductors. Points 83-84, 8586 are adjacent conductors of adjoining tree conductors of opposite polarity. Points 81-88, 89-90 are rectangular resistive wires, and points 9I--92, 9394, 95-96, 91-98 are diagonal resistive wires in the same elemental resistor square with the rectangular resistive wires, forming electrical connections in parallel with the conductors at 99, I00, IOI, I02. Obviously the two systems 'of resistive wires may be of different diameters and resistivities. The resistive square just described is one of nine shown in the figure and the pattern may be extended to any dimensions.

In Figure 9 with rectangular conductor arrangement a pair of resistive wires cross the conductor square and another pair of resistive wires cross the first pair at right angles thereto, making here a symmetrical pattern. Points I03-I04 and I05--I06 are adjacent conductors of adjoining tree conductors of opposite polarity. Points I0I-I08 and I09-IIO are the first pair of resistive wires and III-I I2 and II3-I I4 are the second pair of resistive wires forming an elemental resistive unit of another pattern with electrical connection between conductors and resistors at H5, H6, H1, H8, H8, I20, I2I and I22. Similar connections come at all the other resistive squares and this arrangement is clearly extensible to any length by branching the tree conductors, as seen in the earlier figures. It is; to be noted that the spacing of the resistive wires is unequal although the pattern remains symmetrical.

In Figure 10 is shown a rectangular arrangement of branching conductors with the resistive: wires in rectangular arrangement, but crossing the conductors at an angle of degrees in two sets symmetrically arranged and connected in at the mid points of the conductive wires forming the boundary of each resistor element.

Points I23-I24 and I25--I26 are a pair of adjacent tree conductors, being sub-branched from a larger tree conductor. Points I2II28 and I29I30 are a pair of adjacent resistor wires diagonally crossing said conductor wires with points I3II32 and I33I34 forming another pair of resistor wires crossing the first pair of resistor wires at right angles, and the conductor wires diagonally, forming a resistor element with electrical contacts at I35, I36, I31 and I38.

In Figure 11 is disclosed an arrangement of conductive and resistive wires in which the branch conductors are at an angle other than a right angle to the trunk conductors, and the resistive wires cross the conductors at an angle. This. grouping of resistor elements shows the resistive wires in a minute helical coil. Obviously this pattern may be extended as shown in the preceding figures.

Points I39-I40 and I4I I42 are tree conductors branched by cross-conductors I4I-I43, I44-I45, I46-I4I. The helical resistors 8-449, I43-I49, I43I50, I50--I6I lie between the cross-conductors in parallel connection, and extending in straight lines across all conductors. Instead of helical coiled resistors, there may be straight resistors.

In Figure 12 is shown an arrangement of conductive wires in which equal hexagonal figures are formed in close symmetrical space without. any intermediate bare spots between. Each resistive wire lies in an axis at right angles to the sides of the hexagon. These resistive wires, it will be observed, are in straight lines; parallel to each other, in each of the three respective sets, forming close equilateral triangles, with the apices of said equilateral triangles lying at the centers of the adjacent hexagons, thus utilizing properties of these geometrical figures susceptible of mathematical proof.

' This pattern may be grouped as in the preceding figures and arranged with a transformer or auto transformer with inside or outside taps.

Points I52 and I53 begin conductors terminating respectively-in points IBI and I62, being a pair of adjacent conductors of opposite polarity upon which is uniformly impressed any selected voltage. Three adjacent sides of the hexagonal resistor element are of one polarity and the opposite three likewise adjacent, are of opposite polarity. Resistive wires cross all hexagonal conductors areas in straight lines and electrical connection occurs at points I63, I64, I and I66 and I61, I68 respectively in the hexagonal resistor unit defined by these points. Obviously all hexagonal elements lying between these adjacent conductors receive precisely the same impressed voltage; also this pair of adjacent conductors zigzagging in hexagonal relation, are precisely analogous to conductors in Figure 1 leading from I to I5 and 3 to 4 or 5 to 6 or more distant distinct conductors, with this difference only, that the shapes are different, while the functions of tree-conductors remain unchanged.

It is to be noted that this pattern may have rows of resistor elements connected, as in Figure 16 for three-phase current by connecting in series every fourth conductor and similarly for the intermediate conductors all in the manner as shown in the aforesaid Figure 16, to be more particularly noticed hereinafter.

In Figure 13 are shown a group of-four resistor sheets each composed of resistor elements. These resistor sheets are grouped in parallel connection to a drum controller so that they are successively cut into circuit or dropped out of circuit. An equal voltage is supplied to all four through the said controller, hereinafter called a group controller, and another controller connected to inside taps on a transformer in which the arrangement is such that only one tap is in circuit at one time. This second controller is called a multi-tap controller. Thermolinks are shown in the primary transformer circuit and in the secondary transformer circuit for the purpose of interrupting the circuit on over-temperature.

The circuit comprises an auto transformer a which is protected by a thermo link b. A secondary terminal 0 of the transformer is connected through a thermo link d to the drum e of a control switch J. Other taps g, h, I, j are connected to terminals 01, hi, 11, 7'1 in a controller is having a movable contactor l for selective connection to taps g, h, i, 7'. The contactor l is connected through conductor m to corresponding terminals of a plurality of resistor networks 11, o, p, q. These networks are connected to terminals r, s, t, u respectively which may be selectively connected to drum e. With this connection the voltage applied to networks is controlled at controller k. The controller I controls distribution of electricity as between the resistors or p) q- Figure 25 shows a group of resistive sheets 256, 251 and 258 in multiple connection, and a second group 259, 260 and 26I in multiple connection also. 263 and 264 show multiple service wires connected to a conventional controller. Connectors 262 put the two multiple groups into series connection between the third and fourth control steps. It will be noted that the resistive sheets all lie within a single heating body.

The quantity of heat released within a resistor sheet or resistor block or within a compound network is capable of the finest gradations or the widest variation desired, through the operation of the multitap controller. If the spacings of the c, g, h, i, 9 etc. are well apart from each other and proportionally spaced according to well known laws of energy input to a circuit, the quantity of high heat release may be many times that of the lowest point of heat release and intermediate points afford definite fractions of high heat release. In this respect there is a marked superiority in heat behavior over the common steam and hot water house radiators in that definite and invariable quantities of heat are released for each selected position of the tap controller, a thing unknown in steam heating practice. The controller acts positively and has none of the idiosyncrasies of the thermal valves found in steam work.

This system of electrical heating where it displaces steam and hot water heating, not only gets rid of the uncertainty of supply regulation but gets rid, too, of the troublesome traps and the dangers of radiator freezing at the same time. For the costly and bulky mains, risers and return lines with innumerable fittings, there is substituted standard electric wiring from the supply source, with all its permanence and flexibility in use.

As seen in the earlier figures the transformer or auto transformer may have the connections and taps arranged so that the resistive blocks take higher voltage than the supply voltage and therefore lower quantities of current, for equal heat inputs, being of advantage in cutting down the quantity of alloy resistive material within the resistive block.

Likewise it is well known that the resistive drop with some metals may be as much as 100 volts to the inch of linear resistive conductor for incandescent temperatures, which is contemplated in some types of heating work. In this case, the transformer steps up the voltage for use, but the high voltage utilizing circuit is carried wholly and only within the insulating block.

The group controller itself presents the unique feature of definitely selecting the number of resistor sheets or resistor blocks In circuit. This feature is unknown in steam practice being analogous to cutting in for heating one or more sections of a steam radiator while holding the remaining sections cold. It means economical use of electricity and the avoidance of disagreeable and wasteful overheating, so common during mild weather operation.

In Figure 14 are shown two resistive sheets I68, I10 and I10, I1I in which the conductor I10, I12 is the neutral of a three-wire singlephase or a three-wire direct-current supply. Likewise this assembly may obviously be encrgized by three-wire two-phase supply. Such a compound network may be grouped with similar ones in series or series-multiple groupings.

In Figure 15 is shown one arrangement of six resistive sheets in which a three-wire threephase supply is received by a group of six resistor sheets I13--I82, I14-I03, I15-I and I11I82, I10I83, I19-I84, in which the closed tree conductor I8II8l is a neutral conductor.

Three-phase distribution is readily attained by open delta, closed delta and star grouping, whether the resistive sheet lie in one or several planes, of which two or more may be parallel to 'each other, relationships of importance in building up a resistive block.

In Figure 16 is shown a group of parallel spaced tree conductors separated from each other for the purpose of clarifying the connection shown therein, and likewise there is omission of the resistive wires between the branch conductors. It will be seen that tree conductor I85-l06 is connected in series with the third tree conductor from it in progression, I9l-I92, from which a conducting connector runs to point I91 and from the opposite end of that tree forward to its next conductor, constituting a wave winding series, of which the adjacent resistive elements are supplied by one phase. The next adjacent forward tree conductor I01- I88 is connected to tree conductor |93-I94 and on the opposite side carries forward to its third conductor HIS-200, constituting a similar series circuit forming a second phase circuit; likewise, tree conductor I89-I90 is connected to its third tree conductor ahead of it, l96-l95, and on the opposite side to the third conductor forward, 20I202, constituting a series winding for the third phase.

Obviously, the method of connecting groups of resistor elements disclosed in Figure 16 permits them to be energized by balanced threephase current over very large areas.

In Figure 17 is a front elevation of a wall heater to be set within the wall and approximately flush with the surface thereof, composed of a casing 203 divided by a partition at 204, into two compartments, the larger one in this figure showing a number of resistive blocks, 205, each containing a plurality of resistive sheets. These blocks are connected in parallel at 206 by a conducting rod 201, picking up all front connections of the resistive blocks, 205. The back connections are carried from the block at 200 into a wiring well 200. This wiring well forms an integral part of the casing lying at the back thereof. The whole is covered by a grill 223.

The smaller division of the casing contains a group controller 224 united to the wiring well by a conduit 225 which carries conducting wires from each of the resistive blocks to the said group controller. The lower terminal of the group controller 224 is in electrical connection by the circuit .wire 226 with one of the service wires at 221. The other service wire enters the auto transformer and from the intervening winding selected taps 226 are taken oil, applying the variable voltage through the multitap controller 230 to the resistive blocks by the circuit connector 231. Thermo-links show at 256.

, The group controller 224 determines the number of resistive blocks in circuit, cutting them in successively as more clearly revealed by the circuit diagram shown in Figure 13.

Both controllers have turn knobs 232 and 238 respectively for manual operations, though this action may be automatic with the thermo links through the action of the well known rela system.

Following the circuit diagram of Figure 13, taps from. auto transformer 226 to the multitap controller (k) 230 are shown, said taps being g, h, i, 1, etc. of said circuit diagram. Connector 23l is conductor 11!. of circuit drawing and connector 226 is conductor leading from c to e, 0 being point 221 and e the drum of the multitap controller. The wires leading from said controller 224 via the conduit 225 to resistive blocks 205, are the conductors leaving the multi-controller fingers, r, s, t, u, etc., and connecting to the compound resistive networks diagrammatically shown in n. o, p, q of the circuit drawings.

For a two or three-phase circuit a multi-tap controller similar to Figure 13, but of the balanced type, with two or three-phase transformer is used, being merely two or three circuits identical with Figure 13. actuated by contactor, or separate contactors moving in unison.

While the three electrical parts, auto-transformer and said two controllers are shown within the smaller division of the casing, it is obvious that since they are electrically separated from the nest of resistive blocks specially, they can be placed at any convenient point removed from the radiator, or the three parts may be separated from each other.

The Figures 17, 18, 19 and the circuit diagram are two-wire, that is a single circuit, but this is to be considered symbolic of two, three or more circuits with two, three or more phase circuit supply. The controllers would then be balanced with one drum for each phase and each phase contactor drum mounted on a single shaft. With balanced controllers, the circuits would be all identical with the single circuit of the diagram, Figure 13, and the drawing Figure 17.

Foot blocks attached to the casing are shown at 220 which carry the casing from the floor and permit the entry of air into the casing between the resistive blocks which are mounted vertically and at equal spaces, so that the air is heated thereby and rises through top openings as shown.

In Figure 18 is shown a vertical cross-section at XVIII-XVIII in Figure 17, in which is disclosed a method of keying the resistive blocks into a perforated interlocking base plate at the bottom of the casing and the fastening of the same at the top.

In Figure 18 are also shown the details of the wiring well. The back wall of the casing is composed of two pieces, one upper piece 2) and a lower piece 2 welded together at 2l2. The lower piece projects upwardly beyond the offset H3 and carries acrossits front a narrow shelf 2 to receive the lower edge of a curved deilection plate 215 fastened to the casing at 216 by screw bolt or equivalent means.

The resistive blocks 206 rest upon a perfo-. rated bas plate 211 carrying recessed walls or cheeks to receive the resistive blocks and interlock with said blocks at 2, being in turn fastened by screws or equivalent means at 2|! to the rear wall of the main casing, all so that said resistive blocks are rigidly interlocked on the base plate 211 and held thereto by the screws 2. The resistive block is sections-lined to show one of the compound heating networks with set-screws 222 for making attachment to the foregoing circuit.

In Figure 19 is a view of the heater on line XIXXIX of Figure 17, showing the openings 221, the perforated-base plate 211 for the introduction of air, and the casing perforated to correspond with the base plate openings.

In Figure 20 is shown a radiant wall heater comprised of four radiator units mounted symmetrically in front of a parabolic mirror 241, which consists, in this drawing, of two similar ruled surfaces. parabolic in section and provided at the bottom and top with deflecting plates formed by pressing the parabolic mirror forward at the bottom and the top as shown at X-Y. The casing 224 is divided into two boxes, the larger one containing four radiator units 225 'and the lesser one containing the group controller 226, the multi-tap controller 231, the transformer 226, the whole being covered by a grille 238.

Figure 21 is a cross section along line XXI XXI of Figure 20, showing the radiator units 235 mounted upon the rear of the casing at 240 by screw bolts or equivalent means. The parabolic mirror or reflector 2 appears in section supported upon the back wall of the casing and forming therein a large space for the circulation of air admitted at 242 (see Figure 20) and discharged at 248, respectively, lower and upper portions of the casing.

In Figure 22 is shown a portion of an electrically heated window in which the tree conductors joined by resistive wires appear, and current is supplied at 245. The window is composed of two sheets spacially separated by spanners in the frame, the latter containing openings for the circulation of air between the sheets of glass, admitting air at the bottom of the sash and discharging it at the top of the sash. The construction is better seen in cross-section in Figure 23, which is a section of Figure 22 on line XXIII-mil.

In Figure 23 the resistive sheets are shown at 246 and 241 separated by spanners at 246 which contain long openings 24! communicating with passageway 256 which communicates either with the interior of the room or the outside atmosphere by moving damper 25l by push rod 252. The resistive sheet 241 fits snugly into the frame and the spanner strips 248 are placed in position when the second resistive sheet 246 is put into position as shown. Next, wedge strips 253 securely lock the assemblage into the frame. In this arrangement we have the analogue of the equi-spaced blocks of the wall heater, each sheet of glass'belng the equivalent of an insulating block in the wall heater.

In Figure 24 is shown an assembled sheet of glass in which resistive sheet 254 lies very close to one surface, and resistive sheet 255 lies very close to 254. It is obvious that these resistive sheets may be placed closely together, with this limiting condition only, that the intervening dielectric space should not break down under mechanical or electrical stress.

I claim:

1. As an article of manufacture, a heating body of relatively non-conducting material having embedded therein a plurality of branching conductor wires, each branch being energized from a source of potential, a plurality of branching conductor wires interspaced between the first mentioned conductor wires and not being directly energized from a source of potential, and a group of networks of resistor wires imbedded in the heating body and bridging the branches of the first and second mentioned conductor wires respectively, one or more such networks occupying space between the above mentioned conductor wires, said second mentioned conductor wires serving to distribute and collect the current to and from each resistor network, the whole constituting a plurality of electrically connected series-parallel circuits, and forming a compound electrical network.

2 As an article of manufacture, a heating body of relatively non-conducting material having imbedded therein a plurality of sets of branching conductor wires, each set being energized from a source of potential, a plurality of networks of resistor wires fed by said plurality of branching conductor wires, the resistor wires bridging the conductor wires; and floating conductor wires likewise branching in themselves and not connected to a source of potential, and serving to distribute and collect current to and from each network, the whole constituting a plurality of electrically connected series and parallel circuits, and forming a compound electrical network.

3. The combination of a compound electrical network of electrical conductors in a heating body, said compound electrical network comprising a resistive network of poorly conducting material, and symmetrical groups of branching conductors having better current characteristics, which apply clectromotive force to said resis tive network at a plurality of points internal of the compound electrical network, with an equalizing winding connected to said branching conductors to control voltage drop through the compound electrical network.

4. The combination of a compound electrical network of electrical conductors in a heating body, said compound electrical network comprising a resistive network of poorly conducting material, and symmetrical groups of branching eonductors having better current characteristics, which apply electromotive force to said resistive network at a plurality of points internal of the compound electrical network, with an equalizing winding connected to said branching conductors to control the voltage drop through the compound network, and floating conductors branching to the resistive network and intermediate in position to the conductors connected to the equalizing windings.

5. The combination in an electrical network; of a plurality of electrical resistors lying between non-continuous, intermediate, branching conductor systems, symmetrically branched upon the said resistors to form an electrical network; of other branching conductors joined to said network to form a wider electrical network, said members imbedded in a heating body; with an equalizing winding suitably tapped to said latter branching conductors.

6. As an article of manufacture, a radiating compound resistive network of the type described in claim 5, imbedded in a body of material, which in turn becomes when heated by the resistor elements in said network, a secondary radiating body.

7. A heater comprising a supporting frame, a plurality of electrical heating units, means for supporting said units in spaced relation to said frame to permit passage of air currents around and across said heating units, the latter each comprising a resistive network of electrical conductors, a group of non-continuous, intermediate branching conductors connected to the resistive network at a plurality of points, some of which intermediate branching conductors are connected to a control winding for the purpose of controlling the voltage drop across the soformed compound electrical network.

8. A heater comprising a supporting frame and deflecting means disposed between electrical heating units and said frame, a plurality of electrical heating units, means for supporting said units in spaced relations to said frame to permit passage of air currents around and across said heating units, means for selectively putting successively into circuit, heating units, each of which comprises a resistive network of electrical conductors, a group of non-continuous intermediate branching conductors connected to the resistive network at a plurality of points and a second group of feeding conductors of different polarity connected to the intermediate conductors for completing a supply circuit energized by polyphase alternating current, so forming in each heating unit a compound electrical net work.

9. An elecrical wall heater comprising an open box casing covered by a front grid, a plurality of resistive sheets therein supplied by current conductors lying in a. wiring well integral with the box casing, each of said resistive sheets composed of compound electrical resistive networks imbedded in a relatively non-conducting body, said resistive sheets being at right angles to the grid in close spaced relation to each other and to the supporting frame, to define definite fluid passageways of a considerable dimension parallel to said resistive sheets and narrow crosswise thereof, to permit rising air currents iniroduced through a perforated bottom piece to which said resistive sheets are spatially keyed, to be divided into thin air columns, said air defiected at the top of the box casing outwardly by a curved deflector internal thereof, all of said parts being grouped in one vertical compartment and control means grouped in an adjacent vertical compartment formed by a dividing wall internal of the box casing.

10. The combination with a body of transparent material of a heating network disposed adjacent to the surface thereof and comprising a plurality of branching conductor wires, each branch being energized from a source of potential, a plurality of branching intermediate conductors interspaced between the first mentioned conductor wires and not directly energized from a source of potential and a group of networks of resistive wires imbedded in the transparent body and bridging the branches of the first and second mentioned conductor wires respectively, one or more such networks occupying space between conductor wires, said second mentioned conducting wires serving to distribute and collect current to and from each resistive network,

whereby the heat delivered by the network to said transparent medium is uniformly applied.

11. In an electrically heated window a pair of spaced transparent resistive sheets, each of said resistive sheets composed of compound electrical resistive networks and formed by branching conductive systems, other intermediate branching conductive systems, the branches of which are brought symmetrically close to corresponding branches of the first mentioned systems and networks of resitive material bridging across all branch conductors, said spaced resistive sheets forming with the sashes oi the window a box with all air entering the bottom of the box through openings and rising in the box between the heated side walls, discharging at the top of the box through openings into the space to be heated.

12. A multiple electrical radiant heater comprising an open box casing covered by a front grid, and supporting on its rear wall a multiple cylindrical mirror of parabolic section warped at the top and bottom forwardly in the box to assist entering air at the bottom of the casing and to deflect departing air heated by said multiple cylindrical mirror which in turn is heated by associated radiant resistive blocks each composed of compound electrical resistive networks embedded in a block of relatively non-conducting body material, said compound electrical networks formed by a plurality of branching conductor wireseach branch being energized from a source of potential, a plurality of branching intermediate conductors interspaced between the first mentioned conductor wires and not directly energized from a source of potential and a group 01 networks of resistive wires embedded in the resistive block and bridging the branches of the first and second mentioned conductor wires respectively, one or more such networks occupying space between conductor wires, said second mentioned conductor wires serving to distribute and collect current to and from each resistive network, whereby the heat delivered by said networks is uniformly distributed through said radiant resistive blocks, with means for supporting said radiant blocks from the box casing in associative relation with said parabolic mirrors.

18. In combination, in an electrical heating unit, a plurality of parallel spaced inductive resistors crossed by another similar group and connected at equal spacings to form an electrical heating network said cross-connected junction points united by a plurality of parallel paths alternately connected to branching supply conductors.

14. A network comprising a plurality of resistive network sheets associated within nonconducting body material, wires within said body material connecting groups of said network sheets electrically in multiple, other wires within said body material connecting said groups of network sheets in series-multiple connection, and means for selectively heating one or more of the network sheets, said network sheets positioned within the body material at diflerently spaced distances from the surfaces of the body material.

15. In a heating body the combination of four conductor paths positioned in a four-sided relation, each comprising a trunk conductor, and branching sub-conductors, two such conductor systems at opposite sides having their branching ends close together but unconnected, and the two others oppositely opposed, united by a branching conductor carrying sub-branches symmetrically disposed between the first two thus forming a third conductive system intermediate the other two, with a group of networks of resistor wires imbedded in the heating body and bridging the branches of the intermediate third system with those of the first two and forming a three-wire network in which the first two conductor systems are the outside legs and the third conductor system is the neutral for a three-wire distribution of energy.

16. In a heating body, the combination of a single conductor path positioned on the three sides of a four-sided figure, with a succession of separate conductor paths lying along the fourth side, each such path comprising a trunk conductor and branching sub-conductors, said first conductor system having its branching ends close to the branching ends of those positioned along the fourth side, with a group of networks of resistor wires imbedded in the heating body and bridging the branches oi the first and latter mentioned conductor systems, the whole forming a network adapted for energization by a polyphase supply of electricity wherein the first conductor system is a neutral with each phase in star connection with the latter conductor systems.

17. In a heating body, the combination of two network systems of the type described in claim 16 effected by uniting the middle portion of the trunk conductors 01' their neutrals in a single conductor whereby a double star connection is formed for polyphase supply by connecting outside trunk conductors of like phase together.

18. In a heating body, the combination of a plurality of parallel spaced tree conductors each comprising a trunk conductor and branching sub-conductors, the ends of which are brought close together from adjacent tree conductors, with a group of networks of resistor wires imbedded in the heating body and bridging the aforesaid conductor branches, end connectors uniting the first tree conductor to every fourth tree conductor in series relation, alternately on one side and then on the other side of the assembly of tree conductors and so forming a continuous phase conductor winding, and similarly for the second, and for the third tree conductor, completing a three-phase conductor system adapted to energize the group of resistive networks in closed delta.

JOHN HAYS SMITH. 

